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The second more recent hypothesis is that spores were an early predecessor of land plants and formed during errors in the meiosis of algae, a hypothesized early ancestor of land plants. [18] Whether spores arose before or after land plants, their contributions to topics in fields like paleontology and plant phylogenetics have been useful. [18]
The fertile leaves appear first; their green color slowly becomes brown as the season progresses and the spores are dropped. The spore-bearing stems persist after the sterile fronds are killed by frost, until the next season. The spores must develop within a few weeks or fail. The Osmundastrum cinnamomeum fern forms huge clonal colonies in ...
The root system is always adventitious. The stem is either underground or aerial. The leaves may be microphylls or megaphylls. Their other common characteristics include vascular plant apomorphies (e.g., vascular tissue) and land plant plesiomorphies (e.g., spore dispersal and the absence of seeds). [1] [2]
The basidia (spore-bearing cells) are shaped like long clubs, four-spored, and measure 25–30 by 4–5 μm. They are smooth or have a few basal protuberances (acanthobasidia). The spores are short-ellipsoid in shape, thin
It is a plant parasite as well as saprophytes on both agricultural and forest trees. It produces stout, dark, branching conidiophores that bear clusters of paler conidia (grey in mass) on denticles from apical ampullae. It is a common outdoor fungus and can be detected in spore trap samples. The fungus is often found growing on indoor plants.
In flowering plants, the operculum, also known as a calyptra, is the cap-like covering or "lid" of the flower or fruit that detaches at maturity. The operculum is formed by the fusion of sepals and/or petals and is usually shed as a single structure as the flower or fruit matures. [ 1 ]
Cladosporium fulvum, cause of tomato leaf mould, has been an important genetic model, in that the genetics of host resistance are understood. [4] In the 1960s, it was estimated that the genus Cladosporium contained around 500 plant-pathogenic and saprotrophic species, [ 5 ] but this number has since been increased to over 772 species. [ 6 ]
The basidia (spore-bearing cells) are ellipsoid to roughly spherical in shape, not or rarely stalked, and typically 15–21 μm wide. They contain two to four septa that divide it into compartments; the septa are most frequently diagonal or vertical.